Chirp measurement apparatus

Abstract

A chirp measurement apparatus includes a splitting section for splitting input signal light to two paths; a first dispersion medium with a total dispersion amount of +D (≠0) at a used wavelength, and a second dispersion medium with a total dispersion amount of −D (≠0) at the used wavelength; first and second nonlinear photo-detecting sections for receiving the signal light beams passing through the first and second dispersion media, and for outputting electric signals with the intensities proportional to nth power of the intensities of the signal light beams, where n is greater than one; and a difference detecting section for computing a difference between the electric signals output from the first and second nonlinear photo-detecting sections, and for outputting a differential signal corresponding to the difference as a chirp signal of the input signal light.

1. A chirp measurement apparatus comprising:
 a dispersion medium with a total dispersion amount of +D (≠0) at the wavelength of an input signal light;  
 linear photo-detecting means for receiving a divided part of the signal light passing through said dispersion medium, and for outputting an electric signal V 1  with intensity proportional to the optical intensity of the received part of the divided signal light;  
 nonlinear photo-detecting means for receiving the other part of divided input signal light for outputting an electric signal V 2  with intensity proportional to nth power of the optical intensity of the received other part of divided input signal light; and  
 normalization means for normalizing the electric signal V 2  output from said nonlinear photo-detecting means to an electric signal V 2 /V 1   n  by the electric signal V 1 , and for outputting the electric signal V 2 /V 1   n  as a chirp signal of the input signal light.  
 
   
   
     2. A dispersion compensating apparatus comprising the chirp measurement apparatus as defined in  claim 1 , and tunable dispersion equalization means for canceling the chirp of the input signal light measured by said chirp measurement apparatus.